Fast and automated tool-changing device with standard conical tool support for digitally controlled bending machine

ABSTRACT

A digitally controlled machine for bending, forming, folding or coiling a bar conventionally includes a frame, and a rotary bending tool for producing bends in different planes. A bar is moved along an axis and is brought through a bending snout associated with the frame, and then through a bending tool which is movable relative to the axis by a motor-driven turner. The bending tool is received by a standard conical tool support, and the turner is combined with means for automatically clamping and unclamping the jaws of a gripper associated with the turner. The jaws of the gripper are automatically unclamped when the turner reaches the end of its axial stroke, away from the bending station, and are automatically clamped when the turner begins its axial movement in the opposite direction, toward the bending station.

BACKGROUND OF THE INVENTION

The present invention relates to a tool-changing device for a digitallycontrolled machine for curving, forming, folding and bending bars orsections.

The main objective of the invention is to produce a fast and automatedtool-changing device, something which did not previously exist formachines of this general type.

SUMMARY OF THE INVENTION

The tool-changing device of the present invention can be used, inparticular, but without limitation, with digitally controlled machineshaving retractable or resettable snouts, such as is described incommonly owned French Patent Application No. 00 04317.

A digitally controlled machine is provided for curving, forming, foldingor bending a bar which conventionally includes a bed (B) and a rotarybending tool (1), of the type shown in FIGS. 1 and 2 of the drawings,for obtaining folds in various planes. A bar to be operated upon ismoved along a line of travel and passed through a folding snout (S)carried by the bed (B) of the machine, and then through a folding tool(3). Axial movement of the folding tool, perpendicular to the line oftravel of the bar, is transmitted from a motor by means of a turner.

In accordance with the present invention, the folding tool is carried bya standard conical tool support, and the turner is combined withautomatic means for controlling a tool-engaging gripper. Jaws of thegripper are loosened when the turner reaches the end of its axialtravel, in a direction away from the folding station, and the jaws areautomatically tightened when the turner begins its axial movement in theopposite direction, i.e., in a direction toward the folding station.

In a preferred but nonlimiting embodiment of the present invention, thefunction of automatically loosening and tightening the gripper is tiedto the function of digitally moving the turner in an axial direction,and such functions are performed by the same means.

The present invention will be better understood with reference to thenon-limiting description of an embodiment of the invention which isprovided below, in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 diagrammatically illustrates the tool-supporting gripper of thepresent invention in a tightened position, for gripping a tool.

FIG. 2 shows the tool-supporting gripper of FIG. 1 in the loosenedposition, for releasing the tool.

DETAILED DESCRIPTION OF THE INVENTION

In the description which follows, the tool-changing device of thepresent invention is combined with an assembly of a type which isalready in use on other machine tools and for various differentmachining applications; namely, a standard assembly which includes aconical tool holder (1) and a gripper (2).

In the embodiment depicted in FIGS. 1 and 2, the tool holder (1),together with the tool (3), is releasably secured by the gripper (2) toa transmission assembly which is generally known as a turner (4), fortransmitting movements from an electric motor (5) which is associatedwith the digitally controlled machine and which is operated responsiveto a controller (C). The turner (4) also makes it possible, in knownfashion, to move the tool holder (1) in translation so as to move thetool (3) away from the folding station, or to position the tool (3) withrespect to the folding station.

In accordance with the present invention, jaws (6) of the gripper (2)are automatically tightened over the tool holder (1), and are loosenedfollowing translational movement of the turner (4), for example, as isillustrated in the embodiment shown in FIGS. 1 and 2.

In the tightened position which is shown in FIG. 1, the jaws (6) of thegripper (2) are compressed inside a narrowed part of a conical stop (7),and grip the end of the tool holder (1). To this end, the screw-nutsystem (8) which provides for axial positioning of the turner (4) drivesthe turner axially in the direction of the motor (5), i.e., in thedirection of the arrow {right arrow over (F)}₁.

At the end of its travel (see FIG. 2), the axle (9) of the screw-nutsystem (8) comes into contact with the end of a rod (13) which providesfor axial guidance of the gripper (2), within the turner (4). Thisdrives the gripper (2) in an axial movement, relative to the turner, inthe direction of the arrow {right arrow over (F)}₂, which is opposite tothe direction of the arrow {right arrow over (F)}₁. The gripper (2)moves closer to the conical stop (7) and the jaws (6), under the effectof a spring which is situated in the gripper (2), so that portions ofthe jaws (6) are received in the widened part of the conical stop (7).As a result, the end of the tool holder (1) is automatically releasedfrom the gripper (2).

A device which is commonly used in machine tools of this general typefor purposes of machining a workpiece (not shown) is capable of changingdifferent assemblies comprised of a tool holder (1) and a tool (3),which are drawn from an automated tool storage rack. Thus, the number offold radii per workpiece becomes limited only by the variety of tools inthe storage rack.

The axial movement of the gripper (2) relative to the turner (4), in thedirection of the arrow {right arrow over (F)}₂, also has the effect ofcompressing a tension spring (10) which is positioned between a movingstop (11) associated with the end of the axial guide rod (13) and afixed stop (12) associated with the turner (4). When the turner (4)begins its return travel, in the direction opposite to the direction ofthe arrow {right arrow over (F)}₁, the spring (10) will automaticallymove the gripper (2) away from the conical stop (7), causing the jaws(6) of the gripper to automatically engage the tool holder (1).

When the spring (10) reaches it normal tension position, which isdefined by the length of the rod (13) which provides for axial guidanceof the gripper (2), the axle (9) of the screw-nut system (8) separatesfrom the end of the rod (13). The gripper (2), in the remainder of itsmovement, then exerts a constant force on the cone or taper of the toolholder (1) which is determined by the spring (10).

In the foregoing embodiment, the functions of automatically looseningand tightening the gripper (6) are tied to the function of digitallymoving the turner (4) in an axial direction, and consequently, thesefunctions are performed by the same means.

It is possible to envisage other embodiments in which the functions ofautomatically tightening and loosening the gripper are separate from thedigital, axial movement function, with the result that the two functionsare then performed by separate means. For example, the tightening andloosening functions can be driven by hydraulic or pneumatic rams, whichcan be external to the turner.

1. A digitally controlled machine for curving, forming, folding andbending a bar, comprising: a bed, a folding snout coupled with the bed,and a rotary bending tool associated with the bed and coupled with thefolding snout, wherein the bending tool is carried by a conical toolsupport for obtaining folds in selected planes, and wherein the bar ismovable along a line of travel through the folding snout and past thebending tool; a turner coupled with a motor and the tool support,wherein the tool support is axially movable by the turner in a directionwhich is perpendicular to the line of travel of the bar; and a grippercoupled with the turner and having jaws for selectively engaging thetool support, wherein the jaws of the gripper are automaticallytightened and loosened so that the jaws are automatically loosened whenthe turner reaches an end of axial travel in a direction away from thebending tool and the folding snout, and so that the jaws areautomatically tightened when the turner moves axially in an oppositedirection, toward the bending tool and the folding snout; wherein theautomatic loosening and tightening of the gripper is coupled withmovement of the turner in an axial direction so that the automaticloosening and tightening of the gripper and the axial movement of theturner is performed by the same apparatus.
 2. The machine of claim 1which further includes a conical stop associated with the turner andcoupled with the gripper, wherein the conical stop includes narrowedportions, and wherein the jaws of the gripper are compressed by thenarrowed portions of the conical stop, for gripping an end of the toolsupport.
 3. The machine of claim 2 which further includes a screw-nutsystem associated with the turner, for axially moving the turnerresponsive to operation of the motor.
 4. The machine of claim 3 whereinthe screw-nut system includes an axle for engaging an end of a rodassociated with the gripper, wherein the rod axially guides the gripperwithin the turner, and wherein, at an end of travel of the axle, thescrew-nut system comes into contact with the end of the rod and drivesthe gripper in an axial movement relative to the turner.
 5. The machineof claim 4 which further includes a first tension spring associated withthe gripper, and wherein, when the gripper is moved toward the conicalstop and the jaws, responsive to the first tension spring, the jaws arereceived in a widened part of the conical stop, automatically releasingthe end of the tool support.
 6. The machine of claim 5 which furtherincludes a second tension spring associated with the axle of thescrew-nut system, wherein the second tension spring is positionedbetween a moving stop associated with an end of the rod of the gripperand a fixed stop associated with the turner, and wherein axial movementof the gripper in a first direction, relative to the turner, compressesthe second tension spring between the moving stop and the fixed stop. 7.The machine of claim 6 wherein, responsive to axial movement of theturner in a second direction opposite to the first direction, the secondtension spring automatically moves the gripper away from the conicalstop, automatically gripping the tool support with the jaws of thegripper.
 8. The machine of claim 7 wherein the rod has a defined length,wherein the second tension spring has a normal tension position which isdefined by the length of the rod, and wherein the axle of the screw-nutsystem separates from the end of the rod when the second tension springreaches the normal tension position.
 9. The machine of claim 8 wherein,following separation of the axle of the screw-nut system from the end ofthe rod, the gripper exerts a constant force on the end of the toolsupport which is determined by the second tension spring.